The ACL plugin in Dovecot before 1.0.3 allows remote authenticated users with the insert right to save certain flags via a (1) COPY or (2) APPEND command.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11558
https://issues.rpath.com/browse/RPL-1621
https://exchange.xforce.ibmcloud.com/vulnerabilities/35767
http://www.securityfocus.com/bid/25182
http://www.redhat.com/support/errata/RHSA-2008-0297.html
http://www.dovecot.org/list/dovecot-news/2007-August/000048.html
http://secunia.com/advisories/30342